1. Field of the Invention
The present invention relates to a paper discharge device which is incorporated into a print device. More particularly, the present invention is drawn to a paper discharge device which can discharge a paper from the print device while preventing the paper from getting out of position and can prevent the generation of crinkles in the paper.
2. Description of Related Art
A conventional paper discharge device incorporated into a print device discharges a paper by temporarily providing a corrugation-like fold to the paper, as shown in FIG. 6. Temporarily bending paper so that the bends run in the direction parallel to the feeding direction of the paper is referred to as corrugating. Therefore, if the paper is fed in the longitudinal direction, the paper is corrugated in the transverse direction thereof. Corrugating is used to ensure that the paper is fed straight toward the feeding direction and does not get out of position. The typical example of the above-mentioned paper discharge device is shown in FIGS. 5 and 6.
FIG. 5 is a sectional view of a print device 100 in which the conventional paper discharge device is installed. The print device 100 generally comprises a paper supply portion 110, a print portion 120 and a paper discharge portion 130. The paper supply portion 110, the print portion 120 and the paper discharge portion 130 are arranged in the vertical direction so they are not arranged in a straight line. Therefore, the capacity and the projection area of the print device 100 is small.
The paper supply portion 110 comprises a paper cassette 112 and a paper feeding portion (not shown). The paper cassette 112 can store papers having various sizes. The paper cassette 112 is detachably installed into the print device 100 through a cassette installation entrance 106 formed on a device frame 102.
The print portion 120 comprises a common print means, such as wire dot heads, thermal heads, ink jet heads, and the like.
FIG. 6 is a front view of the conventional paper discharge device. The paper discharge portion 130 comprises a rib panel 131, ribs 132, a rotational shaft 134, paper discharge rollers 136, a paper empty sensor 138 and a paper discharge tray 140.
The paper discharge tray 140 is provided, either integrally or detachably, on the device frame 102. The paper discharge tray 140 can stack and store many papers A which are discharged from a paper discharge outlet 104 formed on the device frame 102. Moreover, the paper discharge tray 140 is disposed with an inclination such that the paper A is stacked upwardly. Accordingly, many discharged papers A can be stored.
The three paper discharge rollers 136 are fixedly disposed on the rotational shaft 134. The rotational shaft 134 is rotated at a predetermined velocity by a driving source (not shown). As shown in FIG. 5, the paper discharge roller 136 rotate counterclockwise as the rotational shaft 134 rotates. One paper discharge roller 136 is disposed near the center of the rotational shaft 134. The other two paper discharge rollers 136 are each disposed on either side of the center paper discharge roller 136 on the rotational shaft 134 and spaced at a predetermined interval from the center paper discharge roller 136. The center paper discharge roller 136 is disposed so as to come in contact near the center portion of the paper A. Accordingly, even if the size of the paper A is changed, at least the center paper discharge roller 136 comes into contact with the paper A. Therefore, papers A having various sizes can be discharged efficiently by a minimum number of the paper discharge rollers 136.
The ribs 132 are disposed integrally on a rib panel 131. The ribs 132 press the paper A against the paper discharge rollers 136. Moreover, in the convention device, four ribs 132 having the same length are disposed on the rib panel 131. Each paper discharge roller 136 is disposed near the center of the interval between two adjacent ribs 132.
The paper empty sensor 138 detects whether the paper A has discharged. The paper empty sensor 138 is disposed on the rib panel 131 in the vicinity of the center paper discharge roller 136.
Next, the operation of the print device 100 will be explained with reference to FIGS. 5-6. When the print device 100 receives the print command from the host computer (not shown), the paper feeding portion takes up one paper A from the paper cassette 112, and feeds the paper A toward the paper discharge portion 130. Then, the three paper discharge rollers 136 disposed on the rotational shaft 134 rotate when the shaft 136 is rotated by a driving source (not shown). The paper discharge rollers 136 and the ribs 132 corrugate the paper A in the direction perpendicular to the feeding direction of the paper A. The corrugation effect is caused by the cooperative relation of the rollers 136 with the ribs 132. Accordingly, the paper A takes a W-like shape. That is, the center portion of the paper A becomes the top of the corrugation. Under this condition, the paper A is discharged onto the paper discharge tray 140.
In the conventional paper discharge device as shown in FIG. 5, the paper A is fed counterclockwise from the paper supply portion 110 toward the paper discharge portion 130 through the print portion 120. Therefore, just before the paper A reaches the paper discharge portion 130, the paper A is curved convexly with respect to the feeding direction of the paper. But, as described above, the paper A which is curved convexly is corrugated in the paper discharge portion 130 such that the paper A takes a W-like shape in the direction perpendicular to the feeding direction of the paper A. Accordingly, the paper A is crinkled. Especially, crinkles usually occur on the bottom portion of the W-like shape.